Slyfox
09-26-2022, 08:39 AM
I had an issue with my 912uls from way back in March. The problem that cropped up was a rough running on take off when turning on a tight downwind. I found that if I pulled back on the throttle it would smooth out. Well I went through many things to finally have an engine that runs great and smoother than ever before. What eventually fixed my running rough was actually a new carburetor, well a used one, gotten from Hal Stockman. This was my left carburetor that came from the 2-4 side, but because it is a model 4 and they have you switch manifolds, it ended up on the right side. I overhauled that carb with new floats and needle. didn't fix it. In fact what it did was after the engine was hot and running in flight would cause a problem. When I landed it ran very bad and when I shut the engine off and left the electric pump on that carb would pour gas out the vent like a steady stream. turn off the pump and it would still leak out. let it set overnight and next morning was just fine. Hal felt the seat was giving problems, so he sent me another carb. installed and worked like a dream. during this time trying to find my problem I replaced the fuel pump with new. replace my b ignition module ( it wouldn't work on start up) I already replaced the a module for this. THe original modules had green strip and known for this.
One final thing I did to make my rotax run better than ever was to install the manifold upgrade that Hal has that increased the size of the balance pipe to 1 inch between the left and the right side. Wow did that make a huge difference, I have smoother running all the way from about 1500rpm to full throttle. very nice.
I had another problem and that was a kick back on start up, usually happened only once and slipped out the sprag clutch and I was very concerned about that. It was also very hard to start. I put in an earthx battery and upgraded to a b and c regulator. no help.
what really did me good was to install a new starter relay, wow that things starts right up now. my cables are small from the 912ul days and I have a plan to install 6agw wire when I can. that's next.
During all this I did rebuild the gear box, that too was down to 250 on the slip. nice and tight now. take care.
One final thing I did to make my rotax run better than ever was to install the manifold upgrade that Hal has that increased the size of the balance pipe to 1 inch between the left and the right side. Wow did that make a huge difference, I have smoother running all the way from about 1500rpm to full throttle. very nice.
I had another problem and that was a kick back on start up, usually happened only once and slipped out the sprag clutch and I was very concerned about that. It was also very hard to start. I put in an earthx battery and upgraded to a b and c regulator. no help.
what really did me good was to install a new starter relay, wow that things starts right up now. my cables are small from the 912ul days and I have a plan to install 6agw wire when I can. that's next.
During all this I did rebuild the gear box, that too was down to 250 on the slip. nice and tight now. take care.